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Sub-substrate space.

> Date: Tue, 01 Apr 1997 20:30:16 -0500
> From: Jeff & Denise Dietsch <dietsch at voicenet_com>
> Subject: CO2 Plots and Substrate ????


> Oh yeah, one more if you don't mind.  Substrate again:)  In light of the
> Plenum approach of marine tanks, what are anybodies opinions on a plenum
> in a plant tank.  Increased circulation???  And no not a UGF:)  Say a
> diffusion grid for a Flor. fixture with a screen mesh on top, or UG
> plates with a floss or mesh cover.  Just a thought. 

I don't use a standard jaubert setup, but I do have the lazy-man's setup -
UGF plates under substrate, with the lift tubes cut off just above the
substrate.  Some of the tubes are open, and some are fit with screened
caps.  None of them are sealed. 

This allows for some circulation beneath the substrate and I think that
keeps the lower part of the substrate from becoming completely anoxic.
Conceivable, you could also dose fertilizers in the space below the
substrate.  It also serves as a safe haven where trumpet snails can avoid
predation by clown loaches and their relatives.  There might be a few
other advantages as well.  Without the openings provided by the lift
tubes I don't think there would be an advantage.

I doubt seriously that a standard jaubert plenum (typically lighting
diffuser sometimes offset from the bottom with some kind of spacer and
covered with fine screen or fabric) would have any advantage in a planted
tank. Its (claimed) primary role in a reef tank is denitrification and
moderation of substrate redox potential.  Planted tanks tend to low
nitrate levels because of plant uptake of nitrogen so denitrification
isn't particularly important and might be regarded as a Bad Thing.  In
reef tanks the substrate redox potential is probably more effected by
sifters and burrowing greeblies than it is by the plenum; the plenum
probably helps, but the critters do the work.  Of course if you get a
comparable amount of burrowing and sifting going on in a plant tank then
all those nice substrate additives start drifting around.  So might the
plants.  This *is* a Bad Thing.

>Thanks peoples, and I am trimming as fast as I can, the Ludwigia just 
> pushing the lid open.  
> Jeff 
> http://www.voicenet.com/~dietsch/ 

Roger Miller